Method for eliminating magnetism of mobile phone module support coating

Abstract

The invention relates to the technical field of imaging module degaussing treatment, and particularly discloses a method for eliminating magnetism of a mobile phone module support coating, which comprises the following steps: S1, pretreatment; s2, anodic oxidation treatment is conducted, specifically, anodic oxidation is conducted in electrolyte, and a composite oxidation film is formed; s3, zinc replacement treatment: carrying out zinc replacement treatment in a zincate solution to form a thin layer of zinc; s4, activating treatment; s5, electroplating treatment is conducted, specifically, electroplating is conducted in a high-phosphorus chemical nickel electroplating solution, and an electroplated layer is formed; s6, carrying out sealing treatment; and S7, drying treatment. According to the method, the chemical nickel plating layer with high phosphorus content is deposited at low temperature, so that a complete amorphous structure is formed, the magnetic conductivity of the plating layer is low, the magnetic field interference on the Hall component is eliminated, and the accuracy and the stability of an optical anti-vibration function are ensured; through the mode that anodic oxidation, electroplating and sealing treatment are combined, the plating layer is endowed with extremely weak magnetism, and meanwhile excellent corrosion resistance and high hardness are provided.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of degaussing processing of imaging modules, and particularly relates to a method for eliminating the magnetism of a plating layer of a mobile phone module support. BACKGROUND

[0002] With the rapid development of the photography function of smart phones, users have made very high requirements for imaging quality; therefore, high-end mobile phone camera modules generally carry an optical anti-shake system; the core actuator of the optical anti-shake system is a voice coil motor; the anti-shake principle is as follows: the system detects the displacement signal generated by the shaking of the mobile phone in real time, the signal is fed back to the controller, and an accurate reverse electromagnetic force is generated by the mover in the voice coil motor to drive the lens group to perform multi-dimensional micro compensation movement, thereby offsetting the shaking and realizing stable imaging. As can be seen, the purity and stability of the magnetic field environment in which the Hall sensor is located directly determine the accuracy and response speed of the anti-shake positioning.

[0003] In the actual architecture of a mobile phone imaging module, the camera module needs to be fixed in a metal support after assembly; and then the camera module is integrally installed on the mobile phone middle frame; as a part of the electromagnetic environment, the material properties of the camera module will affect the surrounding magnetic field.

[0004] At present, the support is generally made of aluminum alloy; as a non-ferromagnetic material, aluminum alloy will not theoretically interfere with the magnetic field; however, in order to improve the corrosion resistance in complex use environments, enhance the surface hardness to resist wear, and improve the appearance texture, an electroplating process is usually performed on the surface of the aluminum alloy support; the mainstream electroplating layer is a chemical nickel-phosphorus alloy, in which nickel is used to provide high hardness and wear resistance, and phosphorus is used to improve the uniformity and adhesion of the plating layer.

[0005] However, there is a key technical contradiction here: Nickel is a ferromagnetic metal; when the phosphorus content in the electroplating layer is at a medium or low level, the plating layer will exhibit obvious ferromagnetism; this causes the originally non-magnetic support to become an additional magnetic source due to the surface plating layer; this additional and unstable magnetic field will superimpose on the working magnetic field of the voice coil motor, seriously interfering with the judgment of the real shaking displacement of the system, and finally resulting in the failure of the anti-shake function, slow focusing, or blurred imaging.

[0006] In the prior art, although it is known that a high-phosphorus chemical nickel plating layer exhibits non-magnetic properties due to its amorphous structure, simply increasing the phosphorus content will bring new problems: too high phosphorus content (such as more than 12%) will reduce the bonding between metal atoms in the plating layer and increase the bonding between phosphorus atoms, thereby reducing the density and adhesion of the plating layer and making the corrosion resistance of the plating layer decrease instead. SUMMARY

[0007] The present application aims to provide a method for eliminating the magnetism of a mobile phone module support coating, so as to solve the problems in the background art.

[0008] To achieve the above object, the present application provides the following technical scheme. A method for eliminating the magnetism of a mobile phone module support coating, comprising the following steps: S1, pretreatment: the aluminum alloy support is subjected to surface pretreatment such as polishing, sand blasting or wire drawing treatment to remove burrs and optimize surface roughness; then, oil removal cleaning is performed to remove surface grease and dirt; S2, anodic oxidation treatment: the aluminum alloy support is placed in an anodic oxidation production line and subjected to anodic oxidation in an electrolyte, wherein the voltage is controlled at 10-20 V, the current is controlled at 1.0-1.5 A / dm2, the temperature is controlled at 18-22℃, and the time is controlled at 20-40 min, so as to form a composite oxide film on the surface of the aluminum alloy support and provide an attachment basis for subsequent electroplating; S3, zinc replacement treatment: after the aluminum alloy support subjected to the anodic oxidation treatment is cleaned, it is placed in a zincate solution for zinc replacement treatment, wherein the temperature is controlled at 18-25℃, and the time is controlled at 1-2 min, so as to remove the thin aluminum oxide film that may exist on the surface of the aluminum alloy support after anodic oxidation and that can be quickly regenerated, and deposit a thin layer of zinc on the aluminum alloy support matrix to enhance the adhesion between the subsequent reinforced coating and the matrix; S4, activation treatment: after the aluminum alloy support subjected to the zinc replacement treatment is cleaned, it is placed in a dilute acid solution (such as a 90-180 g / L dilute sulfuric acid solution or a 30-60 g / L dilute nitric acid solution) for activation treatment, wherein the temperature is controlled at 18-30℃, and the time is controlled at 30-60 s, so as to remove surface oxides and improve surface activity; S5, electroplating treatment: after the aluminum alloy support subjected to the activation treatment is cleaned, it is placed in a high-phosphorus chemical nickel electroplating solution for electroplating, wherein the temperature is controlled at 35-38℃, the time is controlled at 15-30 min, and the PH value is controlled at 4.5-5.0, so as to form an electroplating layer with a thickness of 3-8 μm and a phosphorus content of 12%-20% on the aluminum alloy support; S6, sealing treatment: after the aluminum alloy support subjected to the electroplating treatment is cleaned, it is returned to the anodic oxidation production line and subjected to sealing treatment in a sealing solution to seal the pores of the composite oxide film and improve corrosion resistance; S7, drying treatment: after the aluminum alloy support subjected to the sealing treatment is cleaned, it is dried at 80-100℃ for 20-40 min to complete the treatment.

[0009] As a further scheme of the present application: in the S1 step, the oil removal cleaning uses an alkaline oil removal agent, and is treated at 40-60°C for 5-10 min, wherein the alkaline oil removal agent comprises the following components: 20-35 g / L sodium carbonate, 10-25 g / L trisodium phosphate, 2-5 g / L EDTA-disodium, and 2-5 g / L anionic surfactant.

[0010] As a further scheme of the present application: in the S2 step, the electrolyte is composed of a sulfuric acid solution and an organic acid solution, and the organic acid solution can be an oxalic acid solution or a citric acid solution, wherein the concentration of the sulfuric acid solution is 150-200 g / L, and the concentration of the organic acid solution is 5-15 g / L.

[0011] As a further scheme of the present application: in the S2 step, the composite oxide film is composed of a barrier layer on the inner side and a porous layer on the outer side, wherein the barrier layer has a dense structure, and the thickness proportional coefficient is 1.0-1.4 nm / V, such as when the voltage is 15 V, the thickness is (1.0-1.4) x 15 = 15-21 nm; the resistance is 10 12 ~10 15 Ω·cm; The porous layer has a porous honeycomb structure, the thickness is 8-15 μm, the pore diameter is 10-30 nm, and the pore wall thickness is 1-2 times the pore diameter.

[0012] As a further scheme of the present application: in the S3 step, the zincate solution comprises the following components: 80-120 g / L sodium hydroxide, 8-15 g / L zinc oxide, 10-20 g / L sodium citrate, and 1-2 g / L sodium nitrate.

[0013] As a further scheme of the present application: in the S5 step, the high-phosphorus chemical nickel plating solution comprises the following components: 25-35 g / L nickel sulfate, 25-40 g / L sodium hypophosphite, 15-30 g / L complexing agent (such as lactic acid, citric acid or glycine), and 10-20 g / L buffer (such as sodium acetate or boric acid).

[0014] As a further scheme of the present application: in the S6 step, the sealing solution is boiling water or a nickel salt solution, wherein when the boiling water is used as the sealing solution, the temperature is controlled at 95-100°C, the time is controlled at 15-30 min, and the PH value is controlled at 5.5-6.5; When the nickel salt solution is used as the sealing solution, the temperature is controlled at 80-85°C, the time is controlled at 15-25 min, and the PH value is controlled at 5.8-6.2; wherein, The nickel salt solution is one of a nickel acetate solution, a nickel fluoride solution or a sodium fluoride solution, wherein the concentration of the nickel acetate solution is controlled to be 4.0-5.5 g / L; and the concentration of the nickel fluoride solution and the sodium fluoride solution is controlled to be 0.5-1.2 g / L.

[0015] Compared with the prior art, the present application has the following advantages: The present application can deposit a high-phosphorus-content chemical nickel plating layer at low temperature, so that the plating layer forms a complete amorphous structure and has low magnetic permeability, thereby fundamentally eliminating the magnetic field interference on the Hall element and ensuring the accuracy and stability of the optical anti-shake function.

[0016] The composite structure is obtained by combining anodic oxidation, electroplating and sealing treatment, which can provide excellent corrosion resistance and high hardness while imparting extremely weak magnetism to the plating layer, and successfully balances the contradiction between non-magnetism, corrosion resistance and wear resistance. DETAILED DESCRIPTION EMBODIMENT

[0017] In the embodiment of the present application, a method for eliminating the magnetism of a mobile phone module support plating layer comprises the following steps: S1, pretreatment: polishing, sandblasting or wire drawing treatment is performed on the aluminum alloy support to remove burrs and optimize the surface roughness; and then the aluminum alloy support is placed into an alkaline degreasing agent composed of 20 g / L sodium carbonate, 10 g / L trisodium phosphate, 2 g / L EDTA-disodium and 2 g / L anionic surfactant, and cleaned at 40℃ for 10 min.

[0018] S2, anodic oxidation treatment: the aluminum alloy support is placed into an electrolyte composed of 150 g / L sulfuric acid solution and 5 g / L oxalic acid solution, and anodically oxidized at a voltage of 10 V, a current of 1.0 A / dm² and a temperature of 18℃ for 40 min.

[0019] S3, zinc displacement treatment: after cleaning, the aluminum alloy support is placed into a zincate solution composed of 80 g / L sodium hydroxide, 8 g / L zinc oxide, 10 g / L sodium citrate and 1 g / L sodium nitrate, and zinc displacement treated at 18℃ for 2 min.

[0020] S4, activation treatment: after cleaning, the aluminum alloy support after zinc displacement treatment is placed into a 90 g / L dilute sulfuric acid solution, and activated at 18℃ for 60 s.

[0021] S5, electroplating treatment: after cleaning, the aluminum alloy support is placed into a high-phosphorus chemical nickel electroplating solution composed of 25 g / L nickel sulfate, 25 g / L sodium hypophosphite, 15 g / L lactic acid and 10 g / L sodium acetate, and the pH value is adjusted to 4.5, and then electroplated at 35℃ for 30 min to form a plating layer with a thickness of 3 μm and a phosphorus content of 20% on the aluminum alloy support.

[0022] S6. Sealing treatment: After cleaning, return to the anodizing production line, put it into boiling water, adjust the pH of the boiling water to 5.5, and seal it at 95℃ for 30 minutes.

[0023] S7. Drying treatment: After cleaning, dry at 80℃ for 40 minutes to complete the treatment.

[0024] Tests and Results: Magnetic properties: Tested using a vibrating sample magnetometer, the coating permeability is 1.001 H / m, which meets the requirements of the anti-shake module for a weak magnetic environment.

[0025] Corrosion resistance: After 72 hours of neutral salt spray testing, no corrosion spots were observed on the surface, with a rating of ≥9.

[0026] Adhesion: Thermal shock test according to ASTM B571 (-40℃~85℃, 100 cycles), no blistering or peeling of the coating. Example

[0027] In this embodiment of the invention, a method for eliminating magnetism in the plating of a mobile phone module bracket includes the following steps: S1. Pretreatment: Polish the aluminum alloy bracket; then immerse it in an alkaline degreasing agent composed of 30g / L sodium carbonate, 15g / L trisodium phosphate, 3g / L EDTA-disodium, and 3g / L anionic surfactant, and clean it at 50℃ for 8 minutes.

[0028] S2. Anodizing treatment: The sample is then placed in an electrolyte consisting of 180 g / L sulfuric acid solution and 19 g / L citric acid solution, and anodized for 30 min at a voltage of 15 V, a current of 1.2 A / dm², and a temperature of 20 °C.

[0029] S3. Zinc replacement treatment: After cleaning, place it in a zincate solution composed of 100 g / L sodium hydroxide, 12 g / L zinc oxide, 15 g / L sodium citrate, and 1.5 g / L sodium nitrate, and perform zinc replacement treatment for 1.5 min at 22°C.

[0030] S4. Activation treatment: After cleaning, place it in a 180g / L dilute sulfuric acid solution and activate it at 22℃ for 45s.

[0031] S5. Electroplating treatment: After cleaning, immerse the sample in a high-phosphorus electroless nickel plating solution composed of 30g / L nickel sulfate, 35g / L sodium hypophosphite, 20g / L citric acid, and 15g / L boric acid. Adjust the pH value to 4.8 and electroplat at 36℃ for 25 minutes to form an electroplated layer with a thickness of 5μm and a phosphorus content of 16% on the aluminum alloy support.

[0032] S6. Sealing treatment: After cleaning, return to the anodizing production line, place it in a 4.0 g / L nickel acetate solution, adjust the pH of the solution to 5.8, and seal it at 80℃ for 25 min.

[0033] S7. Drying treatment: After cleaning the sealed aluminum alloy bracket, dry it at 90℃ for 30 minutes to complete the treatment.

[0034] Tests and Results: Magnetic properties: Tested using a vibrating sample magnetometer, the coating permeability is 1.003 H / m, which meets the requirements of the anti-shake module for a weak magnetic environment.

[0035] Corrosion resistance: After 72 hours of neutral salt spray testing, no corrosion spots were observed on the surface, with a rating of ≥9.

[0036] Adhesion: Thermal shock test according to ASTM B571 (-40℃~85℃, 100 cycles), no blistering or peeling of the coating. Example

[0037] In this embodiment of the invention, a method for eliminating magnetism in the plating of a mobile phone module bracket includes the following steps: S1. Pretreatment: Polish the aluminum alloy bracket; then immerse it in an alkaline degreasing agent composed of 35g / L sodium carbonate, 25g / L trisodium phosphate, 5g / L EDTA-disodium, and 5g / L anionic surfactant, and clean it at 60℃ for 5 minutes.

[0038] S2. Anodizing treatment: The aluminum alloy bracket is placed in the anodizing production line and immersed in an electrolyte consisting of 200g / L sulfuric acid solution and 15g / L citric acid solution. The anodizing treatment is carried out for 20 minutes at a voltage of 20V, a current of 1.5A / dm², and a temperature of 22℃.

[0039] S3. Zinc replacement treatment: After cleaning the anodized aluminum alloy bracket, place it in a zincate solution composed of 120 g / L sodium hydroxide, 15 g / L zinc oxide, 20 g / L sodium citrate, and 2 g / L sodium nitrate, and perform zinc replacement treatment for 1 min at 25°C.

[0040] S4. Activation treatment: After cleaning the zinc-replaced aluminum alloy bracket, place it in a 30g / L dilute nitric acid solution and activate it at 30℃ for 30 seconds.

[0041] S5. Electroplating treatment: After cleaning the activated aluminum alloy bracket, it is placed in a high-phosphorus electroless nickel plating solution composed of 35g / L nickel sulfate, 40g / L sodium hypophosphite, 30g / L glycine and 20g / L boric acid. The pH value is adjusted to 5.0, and electroplating is carried out at 38℃ for 15 minutes to form an electroplating layer with a thickness of 8μm and a phosphorus content of 12% on the aluminum alloy bracket.

[0042] S6. Sealing treatment: After cleaning the electroplated aluminum alloy bracket, return it to the anodizing production line, immerse it in a 1.2g / L nickel fluoride solution, adjust the pH value to 6.2, and seal it at 85℃ for 15min.

[0043] S7. Drying treatment: After cleaning the sealed aluminum alloy bracket, dry it at 100℃ for 20 minutes to complete the treatment.

[0044] Tests and Results: Magnetic properties: Tested using a vibrating sample magnetometer, the coating permeability is 1.007 H / m, which meets the requirements of the anti-shake module for a weak magnetic environment.

[0045] Corrosion resistance: After 72 hours of neutral salt spray testing, no corrosion spots were observed on the surface, with a rating of ≥9.

[0046] Adhesion: Thermal shock test according to ASTM B571 (-40℃~85℃, 100 cycles), no blistering or peeling of the coating.

[0047] Comparative example: Traditional medium-phosphorus electroless nickel plating (6% phosphorus content) is used to directly electroplate onto an aluminum alloy support that has undergone simple pretreatment.

[0048] Test results: Magnetic properties: Tested using a vibrating sample magnetometer, the coating permeability was 1.25 H / m, which significantly interfered with the Hall sensor.

[0049] Corrosion resistance: Obvious corrosion spots appeared after 48 hours of neutral salt spray testing.

[0050] Adhesion: Thermal shock test according to ASTM B571 (-40℃~85℃, 100 cycles), blistering and peeling of the coating occurred.

[0051] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for eliminating magnetism in the plating of a mobile phone module bracket, characterized in that, Includes the following steps: S1. Pretreatment: The aluminum alloy bracket is pretreated to remove burrs and optimize surface roughness; then it is cleaned to remove surface grease and dirt. S2. Anodizing treatment: The aluminum alloy bracket is placed in the anodizing production line and anodized in the electrolyte. The voltage is controlled at 10-20V, the current is controlled at 1.0-1.5A / dm², the temperature is controlled at 18-22℃, and the time is controlled at 20-40min, forming a composite oxide film on the surface of the aluminum alloy bracket. S3. Zinc replacement treatment: After cleaning the anodized aluminum alloy bracket, it is placed in a zincate solution for zinc replacement treatment. The temperature is controlled at 18-25℃ and the time is controlled at 1-2 minutes to remove the aluminum oxide film that may still exist on the surface of the aluminum alloy bracket after anodizing and will regenerate rapidly, and to deposit a thin layer of zinc on the aluminum alloy bracket substrate. S4. Activation treatment: After cleaning the aluminum alloy bracket after zinc replacement treatment, it is placed in a dilute acid solution for activation treatment. The temperature is controlled at 18-30℃ and the time is controlled at 30-60 seconds to remove surface oxides. S5. Electroplating treatment: After cleaning the activated aluminum alloy bracket, it is then placed in a high-phosphorus electroless nickel plating solution for electroplating. The temperature is controlled at 35-38℃, the time is controlled at 15-30min, and the pH value is controlled at 4.5-5.

0. An electroplating layer with a thickness of 3-8μm and a phosphorus content of 12%-20% is formed on the aluminum alloy bracket. S6. Sealing treatment: After cleaning the electroplated aluminum alloy bracket, return it to the anodizing production line and seal it in the sealing solution to seal the pores of the composite oxide film. S7. Drying treatment: After cleaning the sealed aluminum alloy bracket, dry it at 80-100℃ for 20-40 minutes to complete the treatment.

2. The method for eliminating magnetism in the plating of a mobile phone module bracket according to claim 1, characterized in that, In step S1, the degreasing and cleaning process uses an alkaline degreasing agent and is carried out at 40–60°C for 5–10 minutes. The alkaline degreasing agent is composed of the following: 20-35 g / L sodium carbonate, 10-25 g / L trisodium phosphate, 2-5 g / L EDTA-disodium, and 2-5 g / L anionic surfactant.

3. The method for eliminating magnetism in the plating of a mobile phone module bracket according to claim 1, characterized in that, In step S2, the electrolyte consists of a sulfuric acid solution and an organic acid solution, wherein, The concentration of sulfuric acid solution is 150–200 g / L, and the concentration of organic acid solution is 5–15 g / L.

4. The method for eliminating magnetism in the plating of a mobile phone module bracket according to claim 1, characterized in that, In step S2, the composite oxide film consists of an inner barrier layer and an outer porous layer, wherein, The barrier layer has a dense structure with a thickness scaling factor of 1.0–1.4 nm / V and a resistivity of 10⁻⁶. 12 ~10 15 Ω·cm; The porous layer has a porous honeycomb structure with a thickness of 8–15 μm, a pore diameter of 10–30 nm, and a pore wall thickness of 1–2 times the pore diameter.

5. The method for eliminating magnetism in the plating of a mobile phone module bracket according to claim 1, characterized in that, In step S3, the zincate solution has the following composition: 80-120 g / L sodium hydroxide, 8-15 g / L zinc oxide, 10-20 g / L sodium citrate, and 1-2 g / L sodium nitrate.

6. The method for eliminating magnetism in the plating of a mobile phone module bracket according to claim 1, characterized in that, In step S5, the high-phosphorus electroless nickel plating solution is composed of the following: 25-35 g / L nickel sulfate, 25-40 g / L sodium hypophosphite, 15-30 g / L complexing agent, and 10-20 g / L buffer.

7. The method for eliminating magnetism in the plating of a mobile phone module bracket according to claim 1, characterized in that, In step S6, the sealing solution is boiling water or a nickel salt solution, wherein, When using boiling water as the sealing solution, the temperature should be controlled at 95–100℃, the time at 15–30 min, and the pH value at 5.5–6.

5. When using nickel salt solution as the blocking solution, the temperature should be controlled at 80–85℃, the time at 15–25 min, and the pH value at 5.8–6.2; among these, The nickel salt solution is one of nickel acetate solution, nickel fluoride solution, or sodium fluoride solution, wherein the concentration of nickel acetate solution is controlled at 4.0–5.5 g / L; and the concentrations of nickel fluoride solution and sodium fluoride solution are controlled at 0.5–1.2 g / L.